Wing dimorphism in semiaquatic bugs (Hemiptera, Heteroptera, Gerromorpha) as a tool for monitoring streams altered by oil palm plantation in the Amazon

Abstract

Wing polymorphism is common in insects and is generally associated with environmental variation, thus, this characteristic can express different phenotypes under different environmental cues. Thereby, organisms with a greater dispersal capacity are more related to heterogeneous environments, while wingless organisms have a greater investment in reproduction even in habitats with suboptimal conditions. This study evaluated the efficacy of wing dimorphism in semiaquatic bugs as a tool to assess altered streams in oil palm plantations. We sampled 27 streams in the Eastern Amazon, classified in preserved areas and oil palm plantation areas. The total matrix of sites x species was broken down in two derived matrices, deconstructed in wingless and winged individuals. We evaluated the concordance between the derived matrices and the total matrix by Procrustes analysis. For each dataset, we used the t-test to evaluate the richness loss and model selection to assess the effect of environmental variables on species richness. There was a greater number of winged phenotype organisms in the preserved areas. Only the wingless matrix had a structure congruent with the overall community matrix. However, species loss of both wingless and winged individuals was observed in oil palm plantation areas. Wingless species richness was higher in areas with lower water temperature and a more closed canopy. On the other hand, winged species richness was higher at streams with lower temperature, pH, and depth. Also, our results emphasized the relationship between the expression of the winged phenotype and land use in polymorphic species. The greater abundance of winged individuals in preserved areas points to species such as Cylindrostethus palmaris and Brachymetra lata as potential targets for stream monitoring in the Amazon, as they are easily located and identified with no need for collection. These results suggest the wing polymorphism as a good strategy in environmental monitoring due to the reduction of time and financial costs required, also reducing the diversity loss that occurs in conventional biological collections. Additionally, they highlighted the trade-off between dispersal and reproduction in these areas, thus indicating that the wing polymorphic species life-history strategies can explain the environmental changes and contribute to the management of conservation policies for Amazonian aquatic ecosystems.